MODIFIED BITUMENS CONTAINING THERMOPLASTIC POLYMERS

Results of an experimental study are presented which demonstrate that the mechanical and viscoelastic behavior of bitumen, both at high and low temperature, is noticeably improved by addition of thermoplastic polymers such as thermoplastic SBS rubbers and atactic polypropylene. These polymers can be used complementary to each other. Atactic polypropylene decreases the flow of bitumen at room temperature, thus reducing creep. The SBS block copolymer, instead, prevents excessive stiffening of bitumen at low temperature, reducing the brittleness. Characteristics of bitumen-polymer blends depend heavily upon bitumen quality, particularly upon its aromatic content and mixing process.